Handheld electronic devices are used in a wide variety of applications and environments. The ubiquity of such devices as mobile phones, digital still cameras and video cameras, handheld music and media players, portable video game devices and controllers, mobile internet devices (MIDs), personal navigation devices (PNDs), and other handheld devices speaks the popularity and desire for these types of devices. However, controlling the multitude of functions of a handheld device can often be awkward or clumsy, due to the small size of the devices. For example, handheld devices with a button input or touch screen typically require two hands of the user to be effectively used, as well as the close attention of the user when operating the device.
Motion sensors, such as inertial sensors like accelerometers or gyroscopes, can be used in handheld electronic devices. Accelerometers can be used for measuring linear acceleration and gyroscopes can be used for measuring angular velocity of a moved handheld electronic device. The markets for motion sensors include mobile phones, video game controllers, personal digital assistants (PDAs), mobile internet devices (MIDs), personal navigational devices (PNDs), digital still cameras, digital video cameras, remote controls, and many more. For example, mobile phones may use accelerometers to detect the tilt of the device in space, which allows a video picture to be displayed in an orientation corresponding to the tilt. Video game console controllers may use accelerometers to detect motion of the hand controller that is used to provide input to a game. Picture and video stabilization is an important feature in even low- or mid-end digital cameras, where lens or image sensors are shifted to compensate for hand jittering measured by a gyroscope. Global positioning system (GPS) and location based service (LBS) applications rely on determining an accurate location of the device, and motion sensors are often needed when a GPS signal is attenuated or unavailable, or to enhance the accuracy of GPS location finding.
Motion sensing devices provide data communication with various device components in the device using communication interfaces. This communication is often implemented using standard interfaces such as multidrop interfaces that allow multiple device components to be connected to a single bus, and which implement master and slaves on the bus to communicate data. For example, an application processor can act as a master to communicate with other slave components over such a bus. However, in motion sensing devices some data, such as motion data, is required to be communicated at a much faster rate than other types of data to be able to provide accurate sensing of the motion of the device. One problem is that such faster communication can disrupt the communication of other devices on the bus, leading to bottlenecks in data flow and disrupted communications. Dedicated interfaces can be used to provide such faster communication; however, dedicated interfaces allowing such communication are not standardized and limit the market for device components specialized for such interfaces.